Tearing across East Africa right now is a plague of biblical proportions: Hundreds of billions of locusts in swarms the size of major cities are laying waste to the crops in their path. It’s the worst outbreak in 25 years in Ethiopia. In Kenya, make that the worst in seven decades. Fueling the locusts’ destruction is a bounty of vegetation following unusually heavy rains. All that food means the landscape can support a huge number of rapidly breeding insects.